Hmm... I think you should recruit a team to create original resources for you: maybe character sprites, faces, tilesets, maps, etc. Maybe even scripters. With a little originality, your game can stand out enough to be purchased and draw in customers. And, of course, limit the number of potential copyrights (should there be some with the resources you are using... I don't know, maybe?
). They work well for free & public games, but for a game that will be sold you may need it to be more customized. The economy is quite bad and people will often not look to buy games unless they really stand out.
The story so far looks like it has potential. It's all a matter of how well you execute it
Hope that helps
that's just my opinion, you don't have to listen to it haha xD